Patellar (Kneecap) Instability

What is patellar instability?

At the base of your thighbone, there is a slight groove in which your kneecap rests. This groove is referred to as a femoral groove. Whenever you bend or straighten your knee, the kneecap smoothly glides up and down within the femoral groove, allowing you to sit, stand, walk, run and move with ease. Sometimes, the kneecap, also known as the patella, can slip out of the femoral groove and become displaced, this is referred to as patellar instability.

What causes patellar instability?

Patellar instability can occur for a variety of reasons, including direct injury to the knee, non-contact injuries, and structural abnormalities. In children, because of their unique knee structure, even minimum trauma can cause the kneecap to dislocate from the femoral groove. Causes of patellar instability may include:

  • Direct injury or trauma to the knee
  • Having a shallow or uneven femoral groove
  • Having a misaligned or raised kneecap
  • An abrupt shift in direction as the foot remains planted to the ground
  • Having weak leg muscles
  • Having unequal leg strength
  • Sustaining prior knee injuries

What are the symptoms of patellar instability?

Symptoms of an unstable kneecap may include:

  • Knee stiffness and pain
  • Kneecap pain that intensifies with movement
  • Knee pain when sitting
  • Swelling of the knee
  • Knee “cracking” that occurs with movement
  • Feeling your knee buckle
  • Feeling that your knee cannot carry your weight
  • Feeling your knee catch with movement

How is patellar instability diagnosed?

If you are experiencing any of the above symptoms or believe you have an unstable kneecap, an evaluation by an experienced medical professional can help determine the cause of your symptoms. To help diagnose patellar instability, your doctor will begin by going over your medical history and symptoms. Next, your doctor will perform a physical exam of your knee, gently probing your kneecap and assessing bone alignment and muscle strength. Your doctor may also examine your gait as you walk or straighten and bend the affected knee. To ensure that your symptoms are not the result of a similar condition or injury and to view how your kneecap is situated in the femoral groove, your doctor may perform additional testing. Additional testing may include X-rays, MRIs, and other imaging tests.

How is patellar instability treated?

Patellar instability can be treated via both nonsurgical and surgical treatment options. Depending on the severity of the dislocated kneecap, treatment will vary. If the kneecap is fully dislocated, treatment will involve moving the kneecap back to its correct position. This process, known as reduction, can sometimes happen naturally, on its own. If the kneecap is unable to naturally fall back into the femoral groove, your doctor may encourage the process by gently and carefully pressing the kneecap into place.

For partial kneecap dislocations, your doctor may recommend:

  • Knee brace to help support and stabilize the knee
  • Crutches to help take weight off the affected knee and speed up the recovery process
  • Physical therapy and exercise to help improve muscle strength and keep the knee joint in place

When dislocation occurs, the kneecap often becomes damaged and worn. This leads to a “loose” kneecap that no longer fits as securely in the femoral groove as it did prior to the dislocation. Because of this, even after the kneecap is repositioned back into place, dislocation may occur again. Your doctor may recommend that you engage in exercises routines that can help strengthen your leg muscles and help prevent recurring dislocations.

Here at our practice, whenever possible, we aim to first recommend nonsurgical treatments to help restore mobility, alleviate pain, and prevent the progression of damage. However, for chronic, recurring patellar instability, we specialize in and offer surgical treatment options such as arthroscopy and open surgery to help restore knee function. Platelet-rich plasma therapy may also be used to help promote healing, alleviate pain, and enhance recovery time.

If you are experiencing symptoms of patellar instability, a consultation with an orthopedic specialist may be the first step towards diagnosis, treatment, and recovery. Dr. Burrus is an experienced fellowship-trained orthopedic surgeon who is dedicated to providing high-quality, specialized holistic care. Call 512.477.6341 or fill out the form on this page to schedule an appointment.